1. Field of the Invention
The present invention relates to a feed system to be used in a multi-unit apartment complex, such as a condominium building, or a building which houses a plurality of companies (hereinafter, referred to as “residence such as multi-unit apartment complex”). The feed system supplies electrical power obtained from a photovoltaic array (solar panel), which is installed in a balcony of an individual unit of the residence such as a multi-unit apartment complex, to a plurality of electrical loads of the individual unit in a distributed manner.
2. Description of the Related Art
Nowadays, as part of global environmental measures, photovoltaic power systems have been widely put to practical use. The photovoltaic power systems convert solar energy into direct-current (DC) power using a photovoltaic array and convert, by an inverter, the DC power into alternating-current (AC) power so as to be available for supply to electrical loads connected to a commercial electrical power system (for example, see Japanese Patent Application Laid-open No. 09-045950).
In such a photovoltaic power system, the photovoltaic array is installed on the roof of a house or on the rooftop of a building so as to be oriented in the irradiation direction of sunlight. The photovoltaic array is formed by integrating a plurality of photovoltaic modules in a planar arrangement. A string is formed by connecting the plurality of photovoltaic modules in series, and arranged in a single line or in two lines or more in accordance with the number of photovoltaic modules disposed in the photovoltaic array to thereby set the size and capacity.
In addition, the number of power cables provided to take out electrical power generated by the photovoltaic array corresponds to the number of lines of the string, and the generated power is sent from each line of the string to the inverter via the power cables and a joint box. The inverter receives the DC power supplied from the photovoltaic array via the power cables, and converts the DC power into AC power having a commercial frequency and a boosted voltage of 110 V, for example.
The AC power is supplied to electrical loads, such as an illumination light, a refrigerator, a personal computer, and an office machine, which are connected to the commercial electrical power system. Such a photovoltaic power system is installed on the roof of a house or on the rooftop of a building as described above, and is particularly useful in compensating for insufficient electrical power at a time of high power demand for a commercial electrical power system, or the like.
However, such a conventional photovoltaic power apparatus has a configuration in which the photovoltaic array, which is a main component of the photovoltaic power apparatus, is installed on the roof of a single-family house or on the rooftop of a building. Therefore, the equipment and size of the photovoltaic power apparatus are comparatively on a large scale. In particular, a photovoltaic power apparatus having a photovoltaic array installed on the rooftop of a multi-unit apartment complex or building is managed by a manager of the multi-unit apartment complex or building, and used so that electrical power generated by the photovoltaic array is converted, by an inverter, into AC power, which is then distributed to all units in the multi-unit apartment complex or building. Accordingly, the capacities and equipment of the photovoltaic cells, inverter, and the like become on a large scale, which results in a high cost of operation and maintenance of the equipment and a high burden ratio of electrical power rates for each unit.
On the other hand, the power conversion efficiency of the photovoltaic array has been improved and the costs of the photovoltaic array have been significantly reduced due to mass production. As a result, today, it is becoming popular among residents of residences such as a multi-unit apartment complex to install the photovoltaic array and the like at individual units, namely, on their own, to thereby obtain the amount of electrical power required for each of the individual units and use the obtained electrical power to cover all or a part of the electrical power consumption, and, in this way, reduce commercial electrical power consumption (amount of power purchased from an electrical company).